In general, light emitting diodes are semiconductor devices formed of a compound such as GaAs, AlGaAs, GaN, InGaN, AlGaInP, etc., and are being widely used as various types of light sources for optical communications and electronic devices.
One of the most critical factors that determine characteristics of the light emitting diode is the intensity of light. Therefore, there have been many attempts to improve brightness of the light emitting diode through various design changes.
For example, the brightness of the light emitting diode could be improved by forming one or more quantum wells in an active layer generating light using recombination of electrons and holes. Also, there was an attempt to improve brightness of the light emitting diode by controlling the numbers or thickness of the quantum wells or barrier layers.
However, such related art studies are only about maximizing light generated from the active layer itself. However, such a method of improving the brightness of light by changing a structure of the active layer itself is disadvantageous in that designs become complicated depending on materials, and it is difficult to apply the method to actual processes.
A nitride light emitting device according to the related art includes a first conduction type cladding layer (not shown), an active layer (not shown), and a second conduction type cladding layer (not shown).
According to the related art, the second conduction type cladding layer should have a thickness of about 150 nm or more. That is, the layer should be grown to 150 nm or more because a thin layer fails to obtain desired characteristics of the second conduction type cladding layer.
However, the related art has the following problems. First, light loss becomes severe as a thickness of the second cladding layer gets greater, because light generated from a light emitting layer passes through the second cladding layer having a thickness of 150 nm and then is emitted to the outside.
Also, since a length of a current path in a vertical direction increases as the thickness increases, resistance occurs as much, which does not help the light emitting layer and thus causes energy to be wasted.